Loading arms are usually used to load and unload fossil fuels such as crude oil, gasoline, light oil, and natural gases (LNG and LPG) between fossil fuel transport ships and storage tanks on the land. A general loading arm includes, as a support structure, an outer riser erected on the land, an inboard boom pivotally supported on the top portion of the outer riser, an outboard boom having an upper end portion pivotally connected to the upper end portion of the inboard boom, a counterweight mounted on the lower end side of the inboard boom, and the like.
The loading arm also includes, as a fossil fuel transport tube, an inner riser disposed in the outer riser, an inboard arm connected to the inner riser through a swivel joint and disposed on the inboard boom, an outboard arm that has an upper end portion connected to the upper end portion of the inboard arm through the swivel joint and is supported by the outboard boom, an emergency release system (ERS) connected to the lower end portion of the outboard arm through the swivel joint, and a joint portion connected to the ERS through or not through the swivel joint.
A loading arm is also used to transport fossil fuel between a storage tank on the land and a tank track.
Patent literature 1 discloses a loading arm that is used to transport LNG or the like between a tank track and a storage tank, and uses a single-tube flexible pipe. This loading arm includes a gantry, an inboard boom supported on the gantry, an outboard boom connected to the distal end portion of the inboard boom, a rotary joint connected to the lower end of the outboard boom, a track connecting boom supported by the rotary joint, a flexible pipe for the transportation of LNG or the like, which is disposed in a space above the inboard boom and the outboard boom, has a top portion supported on a flexible base of a connecting portion between the inboard boom and the outboard boom, and has a distal end portion supported on the distal end portion of the track connecting arm, and the like.
The liquefied gas receiving loading arm disclosed in patent literature 2 is provided with a liquid receiving tube connected to the loading arm, a liquid draining line branching from the liquid receiving tube, a liquid draining automatic valve provided in the liquid draining line, an inactive gas blowing tube connected to a midway portion of the loading arm, an inactive gas blowing automatic valve provided in the inactive gas blowing tube, first and second automatic valves interposed in a bypass line for bypassing the liquid draining automatic valve of the liquid draining line, a gas detector, and the like, and is configured to automatically perform the gas replacing operation of replacing a gas in the loading arm with an inactive gas.